1. Field of the Invention
The present invention generally relates to communication devices and methods of controlling such devices, and more particularly relates to a TV conference communication device and a method of controlling such a device using the ISDN (integrated services digital network) as a transmission line.
2. Description of the Prior Art
TV conference communication devices with functions defined in the CCITT recommendation H.320, the disclosure of which is hereby incorporated by reference, are expected to be used for holding conferences with remote sites by sending and receiving data of images and of voices through transmission lines. Since such TV conference communication devices are regarded as an important and viable application area of the ISDN, their commercial use, though at its early stage of development, is on an increase.
In the TV conference communication devices of the prior art, however, image quality of moving picture images, which is set at the beginning of a TV conference communication session, is kept unchanged throughout that session. Thus, for example, when body actions of participants become more rapid during the session, images observed at the remote sites cannot show those body actions with a satisfactory clarity. Also, even if one wishes to see the participants on the other side more clearly, image quality satisfying that need cannot be obtained in the prior art.
Accordingly, there is a need in the field of TV conference communication devices for a TV conference communication device and a method of controlling such a device which can change image quality of moving picture images during a session of TV conference communication.